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Yu F, Yang L, Zhang R, Hu F, Yuan Y, Wang Z, Yang W. Low levels of supercoiled mitochondrial DNA are involved in heart failure induced by transverse aortic constriction in mice via an inflammatory response mediated by ZBP1. Exp Cell Res 2024:114187. [PMID: 39069152 DOI: 10.1016/j.yexcr.2024.114187] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2024] [Revised: 07/02/2024] [Accepted: 07/25/2024] [Indexed: 07/30/2024]
Abstract
BACKGROUND Inflammation in the myocardium plays a critical role in cardiac remodeling and the pathophysiology of heart failure (HF). Previous studies have shown that mitochondrial DNA (mtDNA) can exist in different topological forms. However, the specific influence of the ratio of supercoiled/relaxed mtDNA on the inflammatory response in cardiomyocytes remains poorly understood. The aim of this study was to elucidate the differential effects of different mtDNA types on cardiomyocyte inflammation through regulation of ZBP1. MATERIALS AND METHODS A mouse model of HF was established by transverse aortic constriction (TAC) or doxorubicin (Doxo) induction. Histopathological changes were assessed by HE staining. ELISA was used to measure cytokine levels (IL-1β and IL-6). Southern blot analysis was performed to examine the different topology of mtDNA. Pearson correlation analysis was used to determine the correlation between the ratio of supercoiled/relaxed mtDNA and inflammatory cytokines. Reverse transcription quantitative PCR (RT-qPCR) was used to measure the mRNA expression levels of cytokines (IL-1β, IL-6) and Dloop, as an mtDNA marker. RESULTS The ratio of supercoiled to relaxed mtDNA was significantly increased in the myocardium of Doxo-induced mice, whereas no significant changes were observed in TAC-induced mice. The levels of IL-1β and IL-6 were positively correlated with the cytoplasmic mtDNA supercoiled/relaxed circle ratio. Different mtDNA topology has different effects on inflammatory pathways. Low supercoiled mtDNA primarily activates the NF-κB (Ser536) pathway via ZBP1, whereas high supercoiled mtDNA significantly affects the STAT1 and STAT2 pathways. The RIPK3-NF-κB pathway, as a downstream target of ZBP1, mediates the inflammatory response induced by low supercoiled mtDNA. Knockdown of TLR9 enhances the expression of ZBP1, p-NF-κB, and RIPK3 in cardiomyocytes treated with low supercoiled mtDNA, indicating the involvement of TLR9 in the anti-inflammatory role of ZBP1 in low supercoiled mtDNA-induced inflammation. CONCLUSION Different ratios of supercoiled to relaxed mtDNA influence the inflammatory response of cardiomyocytes and contribute to HF through the involvement of ZBP1. ZBP1, together with its downstream inflammatory mechanisms, mediates the inflammatory response induced by a low ratio of supercoiled mtDNA.
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Affiliation(s)
- Fan Yu
- Department of Cardiovascular Surgery, The Second Affiliated Hospital, Jiangxi Medical College, Nanchang University, Nanchang 330006, Jiangxi, China
| | - Lu Yang
- Department of Cardiovascular Surgery, The Second Affiliated Hospital, Jiangxi Medical College, Nanchang University, Nanchang 330006, Jiangxi, China
| | - Rongjie Zhang
- Department of Cardiovascular Surgery, The Second Affiliated Hospital, Jiangxi Medical College, Nanchang University, Nanchang 330006, Jiangxi, China
| | - Fajia Hu
- Department of Cardiovascular Surgery, The Second Affiliated Hospital, Jiangxi Medical College, Nanchang University, Nanchang 330006, Jiangxi, China
| | - Yong Yuan
- Department of Cardiovascular Surgery, The Second Affiliated Hospital, Jiangxi Medical College, Nanchang University, Nanchang 330006, Jiangxi, China
| | - Zixu Wang
- Department of Cardiovascular Surgery, The Second Affiliated Hospital, Jiangxi Medical College, Nanchang University, Nanchang 330006, Jiangxi, China
| | - Wei Yang
- Department of Cardiovascular Surgery, The Second Affiliated Hospital, Jiangxi Medical College, Nanchang University, Nanchang 330006, Jiangxi, China.
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Bugga P, Stoner MW, Manning JR, Mushala BAS, Bhattarai N, Sharifi-Sanjani M, Webster BR, Thapa D, Scott I. Validation of GCN5L1/BLOC1S1/BLOS1 antibodies using knockout cells and tissue. Biochem J 2024; 481:643-651. [PMID: 38683688 DOI: 10.1042/bcj20230302] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Revised: 04/18/2024] [Accepted: 04/29/2024] [Indexed: 05/02/2024]
Abstract
GCN5L1, also known as BLOC1S1 and BLOS1, is a small intracellular protein involved in many key biological processes. Over the last decade, GCN5L1 has been implicated in the regulation of protein lysine acetylation, energy metabolism, endo-lysosomal function, and cellular immune pathways. An increasing number of published papers have used commercially-available reagents to interrogate GCN5L1 function. However, in many cases these reagents have not been rigorously validated, leading to potentially misleading results. In this report we tested several commercially-available antibodies for GCN5L1, and found that two-thirds of those available did not unambiguously detect the protein by western blot in cultured mouse cells or ex vivo liver tissue. These data suggest that previously published studies which used these unverified antibodies to measure GCN5L1 protein abundance, in the absence of other independent methods of corroboration, should be interpreted with appropriate caution.
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Affiliation(s)
- Paramesha Bugga
- Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, PA 15261, U.S.A
- Center for Metabolism and Mitochondrial Medicine, University of Pittsburgh, Pittsburgh, PA 15261, U.S.A
- Division of Cardiology, Department of Medicine, University of Pittsburgh, Pittsburgh, PA 15261, U.S.A
| | - Michael W Stoner
- Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, PA 15261, U.S.A
- Center for Metabolism and Mitochondrial Medicine, University of Pittsburgh, Pittsburgh, PA 15261, U.S.A
- Division of Cardiology, Department of Medicine, University of Pittsburgh, Pittsburgh, PA 15261, U.S.A
| | - Janet R Manning
- Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, PA 15261, U.S.A
- Center for Metabolism and Mitochondrial Medicine, University of Pittsburgh, Pittsburgh, PA 15261, U.S.A
- Division of Cardiology, Department of Medicine, University of Pittsburgh, Pittsburgh, PA 15261, U.S.A
| | - Bellina A S Mushala
- Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, PA 15261, U.S.A
- Center for Metabolism and Mitochondrial Medicine, University of Pittsburgh, Pittsburgh, PA 15261, U.S.A
- Division of Cardiology, Department of Medicine, University of Pittsburgh, Pittsburgh, PA 15261, U.S.A
| | - Nisha Bhattarai
- Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, PA 15261, U.S.A
- Center for Metabolism and Mitochondrial Medicine, University of Pittsburgh, Pittsburgh, PA 15261, U.S.A
- Division of Cardiology, Department of Medicine, University of Pittsburgh, Pittsburgh, PA 15261, U.S.A
| | - Maryam Sharifi-Sanjani
- Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, PA 15261, U.S.A
- Center for Metabolism and Mitochondrial Medicine, University of Pittsburgh, Pittsburgh, PA 15261, U.S.A
- Division of Cardiology, Department of Medicine, University of Pittsburgh, Pittsburgh, PA 15261, U.S.A
| | - Bradley R Webster
- Department of Urology, Roswell Park Cancer Center, Buffalo, NY 14263, U.S.A
| | - Dharendra Thapa
- Department of Human Performance - Exercise Physiology, West Virginia University, Morgantown, WV 26506, U.S.A
| | - Iain Scott
- Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, PA 15261, U.S.A
- Center for Metabolism and Mitochondrial Medicine, University of Pittsburgh, Pittsburgh, PA 15261, U.S.A
- Division of Cardiology, Department of Medicine, University of Pittsburgh, Pittsburgh, PA 15261, U.S.A
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Bugga P, Manning JR, Mushala BAS, Stoner MW, Sembrat J, Scott I. GCN5L1-mediated acetylation prevents Rictor degradation in cardiac cells after hypoxic stress. Cell Signal 2024; 116:111065. [PMID: 38281616 PMCID: PMC10922666 DOI: 10.1016/j.cellsig.2024.111065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2023] [Revised: 01/23/2024] [Accepted: 01/25/2024] [Indexed: 01/30/2024]
Abstract
Cardiomyocyte apoptosis and cardiac fibrosis are the leading causes of mortality in patients with ischemic heart disease. As such, these processes represent potential therapeutic targets to treat heart failure resulting from ischemic insult. We previously demonstrated that the mitochondrial acetyltransferase protein GCN5L1 regulates cardiomyocyte cytoprotective signaling in ischemia-reperfusion injury in vivo and hypoxia-reoxygenation injury in vitro. The current study investigated the mechanism underlying GCN5L1-mediated regulation of the Akt/mTORC2 cardioprotective signaling pathway. Rictor protein levels in cardiac tissues from human ischemic heart disease patients were significantly decreased relative to non-ischemic controls. Rictor protein levels were similarly decreased in cardiac AC16 cells following hypoxic stress, while mRNA levels remained unchanged. The reduction in Rictor protein levels after hypoxia was enhanced by the knockdown of GCN5L1, and was blocked by GCN5L1 overexpression. These findings correlated with changes in Rictor lysine acetylation, which were mediated by GCN5L1 acetyltransferase activity. Rictor degradation was regulated by proteasomal activity, which was antagonized by increased Rictor acetylation. Finally, we found that GCN5L1 knockdown restricted cytoprotective Akt signaling, in conjunction with decreased mTOR abundance and activity. In summary, these studies suggest that GCN5L1 promotes cardioprotective Akt/mTORC2 signaling by maintaining Rictor protein levels through enhanced lysine acetylation.
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Affiliation(s)
- Paramesha Bugga
- Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, PA 15261, United States of America; Center for Metabolism and Mitochondrial Medicine, University of Pittsburgh, Pittsburgh, PA 15261, United States of America; Division of Cardiology, University of Pittsburgh, Pittsburgh, PA 15261, United States of America
| | - Janet R Manning
- Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, PA 15261, United States of America; Center for Metabolism and Mitochondrial Medicine, University of Pittsburgh, Pittsburgh, PA 15261, United States of America; Division of Cardiology, University of Pittsburgh, Pittsburgh, PA 15261, United States of America
| | - Bellina A S Mushala
- Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, PA 15261, United States of America; Center for Metabolism and Mitochondrial Medicine, University of Pittsburgh, Pittsburgh, PA 15261, United States of America; Division of Cardiology, University of Pittsburgh, Pittsburgh, PA 15261, United States of America
| | - Michael W Stoner
- Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, PA 15261, United States of America; Center for Metabolism and Mitochondrial Medicine, University of Pittsburgh, Pittsburgh, PA 15261, United States of America; Division of Cardiology, University of Pittsburgh, Pittsburgh, PA 15261, United States of America
| | - John Sembrat
- Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine, University of Pittsburgh, Pittsburgh, PA 15261, United States of America
| | - Iain Scott
- Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, PA 15261, United States of America; Center for Metabolism and Mitochondrial Medicine, University of Pittsburgh, Pittsburgh, PA 15261, United States of America; Division of Cardiology, University of Pittsburgh, Pittsburgh, PA 15261, United States of America.
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4
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Bugga P, Manning JR, Mushala BA, Stoner MW, Sembrat J, Scott I. GCN5L1-mediated acetylation prevents Rictor degradation in cardiac cells after hypoxic stress. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.26.564170. [PMID: 37961692 PMCID: PMC10634848 DOI: 10.1101/2023.10.26.564170] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
Cardiomyocyte apoptosis and cardiac fibrosis are the leading causes of mortality in patients with ischemic heart disease. As such, these processes represent potential therapeutic targets to treat heart failure resulting from ischemic insult. We previously demonstrated that the mitochondrial acetyltransferase protein GCN5L1 regulates cardiomyocyte cytoprotective signaling in ischemia-reperfusion injury in vivo and hypoxia-reoxygenation injury in vitro. The current study investigated the mechanism underlying GCN5L1-mediated regulation of the Akt/mTORC2 cardioprotective signaling pathway. Rictor protein levels in cardiac tissues from human ischemic heart disease patients were significantly decreased relative to non-ischemic controls. Rictor protein levels were similarly decreased in cardiac AC16 cells following hypoxic stress, while mRNA levels remained unchanged. The reduction in Rictor protein levels after hypoxia was enhanced by the knockdown of GCN5L1, and was blocked by GCN5L1 overexpression. These findings correlated with changes in Rictor lysine acetylation, which were mediated by GCN5L1 acetyltransferase activity. Rictor degradation was regulated by proteasomal activity, which was antagonized by increased Rictor acetylation. Finally, we found that GCN5L1 knockdown restricted cytoprotective Akt signaling, in conjunction with decreased mTOR abundance and activity. In summary, these studies suggest that GCN5L1 promotes cardioprotective Akt/mTORC2 signaling by maintaining Rictor protein levels through enhanced lysine acetylation.
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Affiliation(s)
- Paramesha Bugga
- Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, PA 15261
- Center for Metabolism and Mitochondrial Medicine, University of Pittsburgh, Pittsburgh, PA 15261
- Division of Cardiology, University of Pittsburgh, Pittsburgh, PA 15261
| | - Janet R. Manning
- Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, PA 15261
- Center for Metabolism and Mitochondrial Medicine, University of Pittsburgh, Pittsburgh, PA 15261
- Division of Cardiology, University of Pittsburgh, Pittsburgh, PA 15261
| | - Bellina A.S. Mushala
- Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, PA 15261
- Center for Metabolism and Mitochondrial Medicine, University of Pittsburgh, Pittsburgh, PA 15261
- Division of Cardiology, University of Pittsburgh, Pittsburgh, PA 15261
| | - Michael W. Stoner
- Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, PA 15261
- Center for Metabolism and Mitochondrial Medicine, University of Pittsburgh, Pittsburgh, PA 15261
- Division of Cardiology, University of Pittsburgh, Pittsburgh, PA 15261
| | - John Sembrat
- Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine, University of Pittsburgh, Pittsburgh, PA 15261
| | - Iain Scott
- Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, PA 15261
- Center for Metabolism and Mitochondrial Medicine, University of Pittsburgh, Pittsburgh, PA 15261
- Division of Cardiology, University of Pittsburgh, Pittsburgh, PA 15261
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5
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Bugga P, Stoner MW, Manning JR, Mushala BA, Thapa D, Scott I. Validation of GCN5L1/BLOC1S1/BLOS1 Antibodies Using Knockout Cells and Tissue. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.21.550091. [PMID: 37503156 PMCID: PMC10370191 DOI: 10.1101/2023.07.21.550091] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
GCN5L1, also known as BLOC1S1 and BLOS1, is a small intracellular protein involved in a number of key biological processes. Over the last decade, GCN5L1 has been implicated in the regulation of protein lysine acetylation, energy metabolism, endo-lysosomal function, and cellular immune pathways. An increasing number of published papers have used commercially-available reagents to interrogate GCN5L1 function. However, in many cases these reagents have not been rigorously validated, leading to potentially misleading results. In this report we tested several commercially-available antibodies for GCN5L1, and found that two-thirds of those available did not unambiguously detect the protein by western blot in cultured mouse cells or ex vivo liver tissue. These data suggest that previously published studies which used these unverified antibodies to measure GCN5L1 protein abundance, in the absence of other independent methods of corroboration, should be interpreted with appropriate caution.
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Affiliation(s)
- Paramesha Bugga
- Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, PA 15261
- Center for Metabolism and Mitochondrial Medicine, University of Pittsburgh, Pittsburgh, PA 15261
- Division of Cardiology, Department of Medicine, University of Pittsburgh, Pittsburgh, PA 15261
| | - Michael W. Stoner
- Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, PA 15261
- Center for Metabolism and Mitochondrial Medicine, University of Pittsburgh, Pittsburgh, PA 15261
- Division of Cardiology, Department of Medicine, University of Pittsburgh, Pittsburgh, PA 15261
| | - Janet R. Manning
- Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, PA 15261
- Center for Metabolism and Mitochondrial Medicine, University of Pittsburgh, Pittsburgh, PA 15261
- Division of Cardiology, Department of Medicine, University of Pittsburgh, Pittsburgh, PA 15261
| | - Bellina A.S. Mushala
- Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, PA 15261
- Center for Metabolism and Mitochondrial Medicine, University of Pittsburgh, Pittsburgh, PA 15261
- Division of Cardiology, Department of Medicine, University of Pittsburgh, Pittsburgh, PA 15261
| | - Dharendra Thapa
- Department of Human Performance - Exercise Physiology, West Virginia University, Morgantown, WV 26506
| | - Iain Scott
- Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, PA 15261
- Center for Metabolism and Mitochondrial Medicine, University of Pittsburgh, Pittsburgh, PA 15261
- Division of Cardiology, Department of Medicine, University of Pittsburgh, Pittsburgh, PA 15261
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